Tough call...although it comes down to what will run through either one reliably without causing shorts or without running out of contact and stalling on the insulated length.
Generally, an insulated frog reduces the potential to short axles across differently polarized rails in proximity to the frog. But that means the item needing power must have powered axles spread far enough apart that when one is just leaving the dead frog the rear one is still on powered track, thus keeping the motor/decoder supplied with electricity. If you run longer diesels or steamers, especially ones made in the past 10-15 years, chances are excellent that insulfrog is the safer way to go, particularly with the shorts-sensitive DCC systems. If you are running small switchers, then you may have to power your frogs using toggles and jumpers, or you'll have to use electro-frog turnouts that route the power for you.